Coordination-driven Self-assembly And Study Of Metal-Organic Cage-like Compounds

Metal-organic macrocycles are important models to realize the process of enzyme catalysis Metal organic polyhedrons are kinds of metal ions and toothy ligand structure matching through the coordination of self-assembly to form with a range of skeleton structure of supermolecular compounds, thanks to its strong coordination stability and electrochemical and photochemical properties of rich, make its widely attention.A ligand of two tridentate coordination sitesis is gained from the Schiff base reaction between isophthalic dihydrazide and2-pyridine aldehyde. And also a [4+4] MOP is constructed by the ligand and Co2+through coordination self-assembling, and which can be used as the hydrogen desorption catalysis in a ternary system with the attendance of fluorescein and TEA which is respectively functional as photosensitizer and electron sacrificial agent. The catalysis could form host-guest inclusion compound with fluorescein through hydrogen bond and electrostatic interaction because of the existence of amido bond of MOP. The special microenvironment benefit for catalytic reaction and also could mimic microenviroment in the body of bacteria, even would be able to make the excitation wavelength of photoreaction redshift to visible region.The ligand LBA with two bidentate coordination sites is synthesized based on the Schiff base reaction, which can be used to obtaining Metal-Organic Polyhedrons (MOPs) through coordination self-assembling with transition metal ions, such as, Co2+, Ni2+, Fe2+, Zn2+. The obtained MOPs are all isomorphism tetrahedron because of the directionality of coordination bond between ligand and metal. The mimic enzyme catalysis reaction of hydrogen desorption is carried out under the ternary system, in which, one of the MOPs Co-LBA is used as the catalytic, photosensitizer and electronic sacrificial agent are respectively Ru(bpy)3(PFe)2and ascorbic acid. The hydrogen production of the reaction will increase3.2times when p-benzoquinone is added as electron carrier. Because the host-guest inclusion compound between Co-LBA and p-benzoquinone could accelerate electron transfer, and which is able to enhance the catalytic rate of the hydrogen desorption system. The existence of host-guest inclusion compound is demonstrated by Laser flash photolysis experiment, UV-spectrum and also compared with the mononuclear Co(bpy)3Cl2.